Colloidally stabilized emulsions

ABSTRACT

A filter substrate impregnated with an emulsion polymer, the emulsion polymer being substantially devoid of phenolics and stabilized using a protective colloid.

CROSS-REFERENCE TO RELATED APPLICATIONS

The instant application claims priority to U.S. Provisional ApplicationSer. No. 60/153,441 filed Sep. 10, 1999, the disclosure of which isincorporated herein by reference in its entirety.

FIELD AND BACKGROUND OF THE INVENTION

The present invention relates to colloidally stabilized emulsions, andparticularly colloidally stabilized emulsions having reduced or nophenolics.

Phenolics (e.g., phenol-formaldehyde resins), have been used asadhesives, laminates, molding materials, paints and the like. Ofparticular interest is the use of phenolics as adhesives or binders innon-woven substrates and papers. More specifically, phenolics are usedin bonding of refractory shapes; fiber bonding such as in filters; feltbonding; binding of friction products such as brake pads; inpapermaking; in insulation; in roofing products; and in the binding offoundry sands such as abrasives. Of particular interest is the use ofphenolics in filters. Typically, the filter is provided by impregnatinga continuous roll of paper with a phenolic resole in the form of analcohol solution of a condensate of phenol with formaldehyde. Theimpregnated and saturated paper is heated to remove the solvent(alcohol) and corrugated to increase surface area. The resin is thencured in an oven and the paper is rolled again. The rolls of theimpregnated paper are provided to the filter manufacturer for completionof the process which includes pleating and final curing. Such filtersare used in the both air and oil filtering systems in stationary andmobile internal combustion engines.

Phenolics, however, have disadvantages such as high phenol andformaldehyde levels, brittleness when fully cured, slow curingcharacteristics, instability and poor shelf life. Moreover, phenolics,particularly water-based phenolics, are difficult to use to impregnatefiber substrates. In such impregnation, co-solvents such as alcohols,must be used and then removed.

To this end, it would be desirable to substantially eliminate, or in thealternative, substantially reduce the amount of phenolics used inproducts and with substrates wherein phenolics have traditionally beenused as binders or adhesives.

SUMMARY OF THE INVENTION

The present invention provides compositions wherein phenolics aresubstantially eliminated, substantially reduced or replaced by the useof a colloidally stabilized emulsion polymer. By using the colloidallystabilized polymer of the invention and eliminating or replacing the useof phenolics, a wide variety of polymers having crosslinkablefunctionality such as provided by crosslinkers such as epoxies,polyisocyanates, polyurethanes, N-methylol acrylamide,melamine/formaldehyde and the like, can be used or blended togetherwhile providing properties comparable to those of polymers havingphenolics or of phenolics alone.

Alternatively, the colloidally stabilized emulsion polymers, whenblended with phenolics, are more stable and compatible with phenolics ascompared to surfactant stabilized emulsions. By compatibility, it ismeant that the emulsion polymers, when blended with phenolics, remainstable without coagulating or gelling or becoming a paste over longerperiods of time. Thus, the blended product can be used over extendedperiods of time without concern for instability or degradation ofperformance. Moreover, the need to use undesirable solvents iseliminated.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will now be described more fully hereinafter, inwhich preferred embodiments of the invention are shown. This inventionmay, however, be embodied in different forms and should not be construedas limited to the embodiments set forth herein. Rather, theseembodiments are provided so that this disclosure will be thorough andcomplete, and will fully convey the scope of the invention to thoseskilled in the art.

It is believed that a wide variety of polymers in emulsion form can becolloidally stabilized, particularly with polyvinyl alcohol, andoptionally blended with phenolics. Specific polymers in emulsion forminclude polyvinylacetate, vinylacetate-ethylene(VAE), vinyl acrylics,epoxies, urethanes, acrylics, styrene acrylics, butadiene copolymers,and hybrid emulsions of combinations of the foregoing. The presentinvention can be used in systems to replace phenolics wherein phenolicsare used alone, or can be used in systems wherein phenolics are usedwith other polymers. In the latter, the phenolics can be substantiallyeliminated or can be substantially reduced.

Of particular interest are emulsion polymers that have high levels(i.e., greater than about 15 percent by weight) of nitrogen-containingmonomers such as acrylonitrile. By being able to increase the level ofacrylonitrile, properties such as oil and grease resistance can beimproved without adversely affecting the physical properties contributedto by the phenolics.

As stated above, it is desirable to substantially eliminate the use ofphenolics; however, phenolics may still be used at a reduced level. Thephenols employed in the formation of the phenolic resins generallyinclude any phenol which as heretofore been employed in the formation ofphenolic resins and which are not substituted at either the two orthopositions or at the one ortho and the para position. Such unsubstitutedpositions are necessary for the polymerization reaction to occur.Substituted phenols employed in the formation of the phenolic resinsinclude: alkyl substituted phenols, aryl-substituted phenols,cycloalkyl-substituted phenols, alkenyl-substituted phenols, alkoxysubstituted phenols, aryloxy substituted phenols, andhalogen-substituted phenols. Specific examples of suitable phenolsinclude: phenol, o-cresol, m-cresol, p-cresol, 3,5-xylenol, 3-4-xylenol,3,4,5-trimethylphenol, 3-ethyl phenol, 3,5-diethyl phenol, p-butylphenol, 3,5-dibutyl phenol, p-amyl phenol, p-cyclohexyl phenol, p-octylphenol, 3,5-dicyclohexyl phenol, p-phenyl phenol, p-crotyl phenol,3,5-dimethoxy phenol, 3,4,5-trimethoxy phenol, p-ethoxy phenol, p-butoxyphenol, 3-methyl-4-methyoxy phenol, and p-phenoxy phenol.

The aldehydes reacted with the phenol component can include any of thealdehydes heretofore employed in the formation of phenolic resins andinclude, for example, formaldehyde, and benzaldehyde. In general, thealdehydes employed have the formula R′CHO wherein R′ is a hydrogen orhydrocarbon radical of 1-8 carbon atoms. A particularly preferredphenolic is Resafen 8121 available from Resana, Sao Paulo, Brazil.

With respect to the polymers, of particular interest are the ones withaliphatic conjugated dienes. Suitable aliphatic conjugated dienes are C₄to C₉ dienes and include, for example, butadiene monomers such as1,3-butadiene, 2-methyl-1,3-butadiene, 2-chloro-1,3-butadiene, and thelike, such as described in U.S. Pat. No. 5,900,451 to Krishnan et al.,the disclosure of which is incorporated herein by reference in itsentirety. Blends or copolymers of the diene monomers can also be used.The aliphatic conjugated diene is used in an amount, based on totalweight of the starting monomers, from about to 1 to about 99 percent byweight, preferably from about 5 to about 30 percent by weight, and mostpreferably from about 5 to about 15 percent by weight. A particularlypreferred aliphatic conjugated diene is 1,3-butadiene.

Suitable non-aromatic unsaturated monocarboxylic ester monomers includeacrylates and methacrylates. The acrylates and methacrylates may includefunctional groups such as amino groups, hydroxy groups, epoxy groups andthe like. Exemplary acrylates and methacrylates include methyl acrylate,methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate,butyl methacrylate, 2-ethylhexyl acrylate, glycidyl acrylate, glycidylmethacrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate,hydroxypropyl acrylate, hydroxypropyl methacrylate, isobutylmethacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate,3-chloro-2-hydroxybutyl methacrylate, n-propyl methacrylate and thelike. Exemplary amino-functional methacrylates include t-butylaminoethyl methacrylate and dimethylamino ethyl methacrylate. Suitablenon-aromatic dicarboxylic ester monomers are dialkyl fumarates,itaconates and maleates, with the alkyl group having two to eightcarbons, with or without functional groups. Specific monomers includediethyl and dimethyl fumarates, itaconates and maleates. Other suitablenon-aromatic dicarboxylic ester monomers include di(ethylene glycol)maleate, di(ethylene glycol) itaconate, bis(2-hydroxyethyl) maleate,2-hydroxyethyl methyl fumarate, and the like.

The non-aromatic unsaturated mono- or dicarboxylic ester monomer is usedin an amount, based on total weight of the starting monomers, preferablyfrom about 5 to about 95 percent by weight, and most preferably fromabout 20 to about 80 percent by weight. A particularly preferrednon-aromatic unsaturated monocarboxylic ester monomer is methylmethacrylate.

Various aromatic unsaturated monomers may be used and include, but arenot limited to, styrene and styrene derivatives such asalphamethylstyrene, p-methyl styrene, vinyltoluene, ethylstyrene,tert-butyl styrene, monochlorostyrene, dichlorostyrene, vinyl benzylchloride, fluorostyrene, alkoxystyrenes (e.g., paramethoxystyrene) andthe like. Mixtures of the above may be used. Preferably, styrene isemployed. The aromatic unsaturated monomer is preferably used from about5 to about 95 percent based on the total monomer weight, and morepreferably from about 20 to about 80 percent by weight.

Exemplary nitrogen-containing monomers which may be used include, forexample, acrylonitrile, methacrylonitrile, acrylamide, andmethacrylamide. Acrylonitrile is preferred. Mixtures of the above may beused. The nitrogen-containing monomer is preferably used, for example,in an amount ranging from about 5 to about 95 percent based on the totalweight of the monomers, and more preferably from about 15 to about 80percent by weight.

Known and conventional protective colloids may be employed in theemulsion polymer such as partially and fully hydrolyzed polyvinylalcohols; cellulose, ethers, e.g., hydroxymethyl cellulose, hydroxyethylcellulose, hydroxypropyl cellulose, starch ad start derivatives,carboxymethyl cellulose (CMC); the natural and synthetic gums, e.g., gumtragacanth and gum Arabic, polyacrylic acid; acrylates; poly(vinylalcohol)co(vinyl amine) copolymers and the like. Partially and fullyhydrolyzed polyvinyl alcohols such as those available from Air Products,sold under the trademark Airvol™ are preferred and are preferablyemployed from about 0.1 to about 10 percent based on the weight of thetotal monomer, more preferably from about 0.5 to 5 percent, and mostpreferably from about 1 to about 4 percent.

In accordance with the invention, a polymerizable surfactant whichcontains ethylenic unsaturation is used and is copolymerized with theother monomers during emulsion polymerization. As a result, thesurfactant is incorporated in to the backbone of the polymer and servesto stabilize the latex. Examples of suitable surfactants containingethylenic unsaturation are provided in U.S. Pat. No. 5,296,627 to Tanget al., the disclosure of which is incorporated by reference herein inits entirety.

Various polymerizable surfactants are also described in U.S. Pat. No.5,900,451 to Krishnan et al. A preferred polymerizable surfactant is SAM186N™ sold by PPG Industries, Inc. of Pittsburgh, Pa. The polymerizablesurfactant may be used in various amounts. Specifically, the stabilizedemulsion polymer may include between about 0.1 and about 5 percentpolymerizable surfactant based on the monomer weight, more preferablyfrom about 1 to about 4 weight percent, and most preferably from about 2to about 3 weight percent.

Conventional surfactants may be used in conjunction with the surfactanthaving ethylenic unsaturation described herein. Such surfactants arepreferably of the anionic and nonionic type. The selection of thesesurfactants is apparent to one skilled in the art. Preferred nonionicsurfactants are selected from the family ofalkylphenoxypoly(ethyleneoxy) ethanols where the alkyl group typicallyvarious from C₇-C₁₈ and the ethylene oxide units vary from 4-100 moles.Various preferred surfactants in this class include the ethoxylatedoctyl and nonyl phenols, and in particular ethoxylated nonyl phenolswith a hydrophobic/lipophilic balance (HLB) of 15-19. Non-APE(alkylphenol ethoxylate) surfactants such as ethoxylated alcohols, forexample, Abex 2525, are also preferred. Anionic surfactants can beselected from the broad class of sulfonates, sulfates, ethersulfates,sulfosuccinates, diphenyloxide disulfonates, and the like, and arereadily apparent to anyone skilled in the art.

An unsaturated mono- or dicarboxylic acid monomer may also be includedin the stabilized emulsion polymer. These monomers include, but are notlimited to, acrylic acid, methacrylic acid, itaconic acid, fumaric acid,and maleic acid. Derivatives, blends, and mixtures of the above may alsobe used. The unsaturated mono- or discarboxylic acid monomer may be usedin an amount ranging from about 0 to about 15 percent based on the totalmonomer weight, and more preferably from about 0 to about 5 weightpercent.

Additional comonomers can be added to the stabilized emulsion polymer.Included among such additional comonomers are monoethylenicallyunsaturated substituted aliphatic hydrocarbons such as vinyl chloride,and vinylidene chloride; aliphatic vinyl esters such as vinyl formate,vinyl propionate, vinyl butyrate, vinyl versatate and vinylneodecanoate.

The stabilized emulsion polymer can include additives to enhance itsvarious physical and mechanical properties; the selection of which isreadily apparent to one skilled in the art. For example, crosslinkingagents can be included such as vinylic compounds (e.g., divinylbenzene); allyllic compounds (e.g., allyl methacrylate, diallylmaleate); multifunctional acrylates (e.g., di, tri and tetra(meth)acrylates); self-crosslinking monomers such as N-methylolacrylamide, N-methylol methacrylamide and C₁ to C₄ ethers of thesemonomers respectively (e.g., N-iso[butoxymethoxy] methacrylamide),acrylamido glycolic acid and its esters, and alkyl acrylamido glycolatealkyl ethers (e.g., methylacrylamido glycolate methyl ether). Thecrosslinking agents can be included in amounts of up to about 15 percentby weight, and preferably from about 3 to about 8 percent by weight.Additional monomers such as silanes can be included to improve specificproperties such as latex stability, solvent resistance, as well asadhesion and strength and are described, for example, in U.S. Pat. No.5,830,934 to Krishnan, the disclosure of which is incorporated herein byreference in its entirety.

Initiators which facilitate polymerization are typically used andinclude, for example, materials such as persulfates, organic peroxides,peresters, and azo compounds such as azobis(isobutyronitrile) (AIBN).Persulfate initiators are preferred and include, for example, potassiumpersulfate and ammonium persulfate.

Reductants may be employed in the polymerization, and are typicallyemployed in combination with the initiator as part of a redox system.Suitable reductants include sodium bisulfite, erythorbic acid, ascorbicacid, sodium thiosulfate, sodium formaldehyde sulfoxylate (SFS), and thelike.

Other additives which may be used include other natural and syntheticbinders, fixing agents, wetting agents, plasticizers (e.g., diisodecylphthalate), softeners, foam-inhibiting agents, froth aids, othercrosslinking agents (e.g., melamine formaldehyde resin, epoxies,polyisocyanates, etc.), flame retardants, dispersing agents (e.g.,tetrasodium pyrophosphate), pH adjusting components (e.g., ammoniumhydroxide), sequestering or chelating agents (e.g., ethylenediaminetetraacetic acid (EDTA)) and other components. The selection ofany of these additives is readily apparent to one skilled in the art.

One use of the reduced phenolic/butadiene blend is, for example, thefabrication of filters (e.g., oil filters). In the first or treatingstep, a continuous roll of paper is conventionally impregnated with thebinder in the form of an alcohol solution. When a phenolic is used, thesaturated paper is heated to remove the alcohol (solvent). In thepresent invention, the alcohol solution is not needed and this step iseliminated. The treated paper is then corrugated for the purpose ofincreasing surface area. The corrugated sheet is subsequently conveyedthrough an oven in order to advance the cure of the resinous impregnateto a fusible intermediate or B stage, and then the corrugated sheet ismade into a filter.

The following examples are provided to illustrate the present invention,and should not be construed as limiting the scope thereof.

EXAMPLES Example 1

A polyvinyl alcohol stabilized butadiene emulsion is prepared comprisingthe following: COMPONENT GRAMS Deionized Water 2560.00 EDTA ChelatingAgent 0.80 Dowfax 2A1 Surfactant 3.20 Airvol 103 PVOH 32.00 Abex 2525Surfactant 16.00 Tamol 731A Dispersing Agent 0.80 Sam 186N PolymerizableSurfactant 16.00 Methoxy polyethylene glycol methacrylate 32.00 AmmoniumPersulfate Initiator 0.80 Butadiene 160.00 Tertiary Dodecyl Mercaptan6.40 Acrylonitrile 320.00 Styrene 448.00 Acrylic Acid 16.00Methylmethacrylate 480.00 Butylacrylate 80.00 N-methylol arylamide 64.00Diammonium Phosphate 4.00

Wet performance testing was achieved by boiling the test samples indistilled water for 5 minutes. After the allocated time, the sampleswere removed and blotted dry but kept wet during testing by coveringthem with moist absorbent towels.

Tensile data was generated on substrate tested in the machine direction.Sample size was 1″×5″, with an extension rate of 10 inches/minute, andsamples were tested on an Instron 1125.

The testing was done on No. 4 Whatman Filter Paper. Each sheet had a 20percent add on of the composition of Example 1 is diluted to 22 percenttotal solids, was dried for 4 minutes at 225° F. and was allowed tocondition overnight in a constant temperature/humidity room. Then eachsheet was cured at 350° F. in a forced air oven for the cure times ofthe tables. Max Load (lbf) Max Stn (elong) Max Str (psi) Cure Time (std.dev.) (std. dev.) (std. dev.) Example 1 - Wet Tensile Strength 1′ 11.97(1.07) 4.027 (0.686) 25.75 (7.25) 2′ 13.14 (0.16) 4.210 (0.259) 27.52(3.1) 3′ 14.57 (0.47) 4.487 (0.105) 34.36 (1.25) 4′ 14.04 (0.52) 4.257(0.229) 31.59 (3.17) 5′ 14.15 (0.63) 4.211 (0.298) 31.28 (4.50) 10′ 13.77 (0.79) 3.846 (0.185) 27.01 (2.74) Example 1 - Dry Tensile Strength1′ 26.86 (1.57) 2.929 (0.259) 42.61 (9.17) 2′ 29.50 (1.22) 3.022 (0.183)52.95 (4.99) 3′ 26.64 (1.17) 2.792 (0.229) 41.61 (6.13) 4′ 27.80 (2.03)2.747 (0.396) 46.08 (11.37) 5′ 28.19 (0.68) 2.746 (0.258) 46.41 (6.43)10′  26.83 (2.01) 2.471 (0.317) 38.80 (9.68)

Examples 2-7

Various amounts a phenolic available as Resafen 8121 from Resana, SaoPaulo, Brazil, were added to Example 1, along with phenolic only, andthe tensile strengths measured. The amounts added are as follows:Example Amt (%) of Example 1 Amt (%) of Phenolic 2 98 2 3 96 4 4 94 6 592 8 6 90 10 7 50 50 8 0 100

The wet tensile strength results are as follows: Cure Time Max Load Maxelong Max psi % add-on @350 F. (std. dev.) (std. dev.) (std. dev.)Example 2 19.2 1′ 12.11 (0.38) 4.394 (0.002) 27.12 (1.40) 19.2 2′ 14.84(0.19) 4.669 (0.105) 36.66 (1.29) 19.2 3′ 15.00 (0.81) 4.441 (0.311)34.61 (4.06) 19.6 4′ 14.28 (0.44) 4.393 (0.183) 32.35 (2.13) 19.6 5′14.38 (0.57) 4.396 (0.183) 32.89 (2.77) 19.6 10′  14.26 (0.58) 3.967(0.107) 29.32 (1.75) Example 3 19.9 1′ 14.12 (0.12) 4.821 (0.28)  36.62(2.32) 19.9 2′ 15.38 (1.14) 4.898 (0.345) 39.14 (6.60) 19.9 3′ 14.88(0.27) 4.271 (0.106) 31.13 (0.99) 19.4 4′ 16.35 (1.40) 4.454 (0.529)38.14 (7.74) 19.4 5′ 16.33 (0.83) 4.303 (0.184) 36.45 (5.24) 19.4 10′ 16.11 (0.81) 4.027 (0.258) 31.90 (4.20) Example 4 19.4 1′ 14.00 (0.55)4.897 (0.311) 36.02 (3.47) 19.4 2′ 17.65 (0.97) 5.081 (0.406) 45.86(6.85) 19.4 3′ 17.52 (0.83) 4.806 (0.433) 43.47 (5.51) 19.3 4′ 19.10(0.93) 4.822 (0.280) 47.26 (4.76) 19.3 5′ 18.50 (0.71) 4.577 (0.183)43.58 (3.37) 19.3 10′  19.14 (1.10) 4.347 (0.313) 41.73 (4.38) Example 519.4 1′ 13.35 (1.08) 4.578 (0.539) 32.29 (6.96) 19.4 2′ 18.63 (0.50)5.172 (0.175) 49.29 (3.15) 19.4 3′ 19.49 (0.95) 4.898 (0.405) 48.49(5.48) 19.8 4′ 20.02 (0.72) 4.668 (0.317) 48.06 (4.52) 19.8 5′ 22.05(0.70) 4.943 (0.335) 57.85 (5.97) 19.8 10′  20.79 (1.49) 4.531 (0.347)48.06 (8.20) Example 6 19.5 1′ 15.84 (0.45) 5.127 (0.259)  42.05 (0.281)19.5 2′ 19.36 (0.62) 5.188 (0.212) 50.93 (4.13) 19.5 3′ 20.16 (1.05)4.623 (0.231) 48.82 (5.46) 19.3 4′ 22.59 (0.69) 5.188 (0.212) 60.15(3.89) 19.3 5′ 23.05 (0.93) 4.852 (0.235) 58.31 (5.02) 19.3 10′  22.55(0.86) 4.578 (0.150) 54.30 (3.40) Example 7 19.9 1′ 13.84 (0.99) 5.035(0.57)  33.45 (4.27) 19.9 2′ 21.98 (0.85) 4.669 (0.235) 54.29 (5.16)19.9 3′ 23.79 (1.74) 4.073 (0.347) 52.04 (9.66) 20.1 4′ 26.68 (0.78)3.891 (0.229) 57.95 (4.95) 20.1 5′ 15.26 (0.45) 3.526 (0.092) 49.22(2.34) 20.1 10′  26.06 (2.42) 3.066 (0.525)  44.42 (11.01) Example 8Cure Time Max Load Max elong Max psi Product @350 F. (std. dev.) (std.dev.) (std. dev.) Resafen 1′   11.72 (1.6.29) 1.466 (0.185) 6.711(2.118) 8121 2′ 13.11 (1.11) 1.190 (0.132) 6.031 (0.937) 3′ 13.00 (0.70)1.283 (0.00)  5.490 (0.509) 4′ 9.7222 (1.440) 0.9778 (0.1058) 2.622(0.618) 5′ 12.24 (1.05) 1.097 (0.183) 4.955 (0.621) 10′  12.05 (0.73)1.160 (0.104) 4.533 (0.598)

Example 9

A polyvinyl alcohol stabilized emulsion having more N-methylolacrylamide and no butylacrylate is prepared, comprising the following:COMPONENT GRAMS Deionized Water 2560.00 EDTA Chelating Agent 0.80 Dowfax2A1 Surfactant 3.20 Airvol 103 PVOH 32.00 Abex 2525 Surfactant 16.00Tamol 731A Dispersing Agent 0.80 Sam 186N Polymerizable Surfactant 16.00Methoxy polyethylene glycol methacrylate 32.00 Ammonium PersulfateInitiator 0.80 Butadiene 240.00 Tertiary Dodecyl Mercaptan 6.40Acrylonitrile 320.00 Styrene 704.00 Acrylic Acid 16.00Methylmethacrylate 176.00 N-methylol arylamide 112.00 DiammoniumPhosphate 4.00

The wet tensile strength at different cure rates was as follows: CureTime 350° F. Lbf (std. dev.) Elong (std. dev.) Psi (std. dev.) 1′ 17.41(0.42 5.310 (0.299) 45.57 (4.37) 2′ 17.58 (1.08) 5.004 (0.212) 44.59(6.09) 3′ 17.47 (0.93) 4.822 (0.279) 41.23 (5.58) 4′ 16.89 (0.32) 4.699(0.106) 38.49 (2.96) 5′ 17.32 (0.62) 4.699 (0.212) 40.55 (2.73) 10′ 16.99 (0.58) 4.393 (0.183) 38.19 (2.37)

The above examples illustrate that compositions having no phenolic orreduced phenolic can provide physical properties comparable toconventional emulsion compositions having phenolics.

The foregoing is illustrative of the present invention and is not to beconstrued as limiting thereof. Although a few exemplary embodiments ofthis invention have been described, those skilled in the art willreadily appreciate that many modifications are possible in the exemplaryembodiments without materially departing from the novel teachings andadvantages of this invention. Accordingly, all such modifications areintended to be included within the scope of this invention as defined inthe claims. Therefore, it is to be understood that the foregoing isillustrative of the present invention and is not to be construed aslimited to the specific embodiments disclosed, and that modifications tothe disclosed embodiments, as well as other embodiments, are intended tobe included within the scope of the appended claims. The invention isdefined by the following claims, with equivalents of the claims to beincluded therein.

1. In a system using phenolics alone or in combination with one or moreother polymers, the improvement comprising using an emulsion polymer,which includes crosslinkable functionality and which includes theaddition of a protective colloid, to replace or substantially eliminateor substantially reduce the amount of phenolics.
 2. The system accordingto claim 1, wherein the protective colloid is a polyvinyl alcohol. 3.The system according to claim 2, wherein the polyvinyl alcohol is fullyhydrolyzed.
 4. The system according to claim 2, wherein the polyvinylalcohol is partially hydrolyzed.
 5. The system according to claim 1,wherein the crosslinkable functionality is provided by aself-crosslinking monomer selected from the group consisting ofN-methylol acrylamide, N-methylol methacrylamide and C₁ to C₄ ethersthereof.
 6. A filter comprising a filter substrate impregnated with anemulsion polymer, the emulsion polymer being substantially devoid ofphenolics and stabilized using a protective colloid.
 7. The filteraccording to claim 6, wherein the protective colloid is a polyvinylalcohol.
 8. The filter according to claim 7, wherein the polyvinylalcohol is fully hydrolyzed.
 9. The filter according to claim 7, whereinthe polyvinyl alcohol is partially hydrolyzed.
 10. The filter accordingto claim 6, wherein the emulsion polymer has crosslinkable functionalityprovided by a self-crosslinking monomer selected from the groupconsisting of N-methylol acrylamide, N-methylol methacrylamide and C₁ toC₄ ethers thereof.
 11. A filter comprising a filter substrateimpregnated with an emulsion polymer, the emulsion polymer beingsubstantially devoid of phenolics and stabilized using a polyvinylalcohol.
 12. The filter according to claim 11, wherein the protectivecolloid is a polyvinyl alcohol.
 13. The filter according to claim 12,wherein polyvinyl alcohol is fully hydrolyzed.
 14. The filter accordingto claim 12, wherein the polyvinyl alcohol is partially hydrolyzed. 15.The filter according to claim 11, wherein the emulsion polymer hascrosslinkable functionality provided by a self-crosslinking monomerselected from the group consisting of N-methylol acrylamide, N-methylolmethacrylamide and C₁ to C₄ ethers thereof.